Near-infrared study of open clusters Teutsch 10 and Teutsch 25 D. Bisht a,⇑ , Shashikiran Ganesh a , R.K.S. Yadav b , Alok Durgapal c , Geeta Rangwal c a Astronomy and Astrophysics Division, Physical Research Laboratory, Ahmedabad, India b Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital, India c Department of Physics, DSB Campus, Kumaun University, Nainital, India Received 9 May 2017; received in revised form 9 September 2017; accepted 31 October 2017 Available online 8 November 2017 Abstract The astrophysical parameters have been estimated for two unstudied open star clusters Teutsch 10 and Teutsch 25 using the Two Micron All Sky Survey (2MASS ) database. Radius is estimated as 4.5 arcmin for both clusters using radial density profiles. We have esti- mated proper motion values in both RA and DEC directions as 2:28  0:3 and 0:38  0:11 mas yr 1 for Teutsch 10 and 0:48  0:3 and 3:35  0:16 mas yr 1 for Teutsch 25 using PPMXL 1 catalog. By estimating the stellar membership probabilities, we have identified 30 and 28 most likely members for Teutsch 10 and Teutsch 25 respectively. We have estimated the reddening as EðB  V Þ¼ 0:96  0:3 mag for Teutsch 10 and 0:58  0:2 mag for Teutsch 25, while the corresponding distances are 2:4  0:2 and 1:9  0:1 kpc. Ages of 70  10 Myr for Teutsch 10 and 900  100 Myr for Teutsch 25 are estimated using the theoretical isochrones of metallicity Z = 0.019. The mass func- tion slopes are derived as 1:23  0:30 and 1:09  0:35 for Teutsch 10 and Teutsch 25 respectively. Estimated mass function slope for both the clusters are close to the Salpeter value (x ¼ 1:35) within the errors. Estimated values of dynamical relaxation time are found to be less than cluster’s age for these objects. This concludes that both objects are dynamically relaxed. The possible reason for relaxation may be due to dynamical evolution or imprint of star formation or both. Ó 2017 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Galaxy; Open cluster and associations; Individual; Teutsch 10 and Teutsch 25; Proper-motion; Luminosity and mass function 1. Introduction Open clusters (OCs) are important objects to under- stand star formation process in the Galaxy and in star clus- ters (Lada and Lada, 2003). Piskunov et al. (2006) estimated that the total number of open clusters in the Galactic disk to be the order of 10 5 at present. Gaburov and Gieles (2008) have compiled statistically significant samples of clusters of known distance, age and metallicity. By using the colour-magnitude and colour-colour diagrams of star clusters, it is possible to estimate the fundamental parameters (age, distance and reddening). These funda- mental parameters play most important role to understand about the theories of star formation and stellar evolution process. The 2MASS data has been proved very powerful tool in the investigation of the structure and stellar content of open star clusters (Bonatto and Bica, 2003; Soares and Bica, 2002; Bica et al., 2003; Selim et al., 2014). In the recent years, more than thousands open clusters were dis- covered by analysing 2MASS data (Kronberger et al., 2006; Froebrich et al., 2007; Koposov et al., 2008; Glushkova et al., 2010). The reality of these recently dis- covered open clusters was confirmed by means of their J ; ðJ  H Þ and K s ; ðJ  K s Þ colour magnitude diagram analysis and their fundamental parameters were estimated. Most of the open clusters are embedded in the Galactic disk and also affected by field star contamination, it is https://doi.org/10.1016/j.asr.2017.10.055 0273-1177/Ó 2017 COSPAR. Published by Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: dbisht@prl.res.in (D. Bisht). 1 http://vizer.cfa.harvard.edu/vizbin/VizieR?-source=I/317. www.elsevier.com/locate/asr Available online at www.sciencedirect.com ScienceDirect Advances in Space Research 61 (2018) 571–580